While half of the NHL playoffs' first-round series have reached a conclusion, there are still four series that are up in the air. All of them could go either way, as this year's postseason is one of the most unpredictable in recent memory.

Which remaining series are you most excited for?

Which remaining series are you most excited for?

Penguins vs. Islanders

13.9%

Ducks vs. Red Wings

34.5%

Capitals vs. Rangers

20.1%

Bruins vs. Maple Leafs

31.4%

Total votes: 194

The Pittsburgh Penguins and New York Islanders will do battle in Game 6 on Saturday night, while Sunday's schedule will be stacked with three games. There is a lot of uncertainty surrounding the playoffs due to the fact that no second-round matchups have been determined yet. That should change over the next couple days.

Keep reading for analysis on all four remaining first-round series, as well as predictions for who will ultimately prevail in each matchup.

Pittsburgh Penguins vs. New York Islanders

Perhaps the most surprising series of the playoffs thus far has been the No. 1-seeded Pittsburgh Penguins against the No. 8 New York Islanders. Few observers gave the Isles much of a chance in this series, but they have managed to take two games and will have a chance to take it the distance with a win in Game 6. There is an obvious talent disparity, but New York has played together as a team through the series' first five games.

A big reason for the Islanders' success in this series has been the putrid play of Penguins goalie Marc-Andre Fleury. The defensive play in front of Fleury had not been particularly good either, but head coach Dan Bylsma decided to play backup Tomas Vokoun in Game 5. It paid off, as the Pens prevailed 4-0 and took a crucial 3-1 lead in the series.

Last night the Penguins switched it up & started Tomas Vokoun in goal. Vokoun stopped all 31 shots in a 4-0 win over the Islanders. #Solid

As important as goaltending is, Pittsburgh needs to rely on its talent up front. The Islanders have Hart Trophy candidate John Tavares up front, but no team can match the Penguins' forward group of Sidney Crosby, Evgeni Malkin, Jarome Iginla, James Neal and Chris Kunitz.

Expect the Pens' superior skill to be showcased in Game 6 as they put an end to New York's Cinderella season.

Anaheim Ducks vs. Detroit Red Wings

The Anaheim Ducks and Detroit Red Wings are set to take part in the first Game 7 of these playoffs, as the Wings were able to even the series at 3-3 with a Game 6 victory. Detroit forward Henrik Zetterberg scored the overtime winner at home on an absolutely beautiful play. Zetterberg has had a lot of playoff success over the years, but that playoff OT goal was amazingly the first of his career, according to ESPN.

Henrik Zetterberg: 1st career postseason OT goal in his 115th career postseason game. wins it for Red Wings

While the Ducks have actually carried much of the play in this series and have won a couple of their games by wide margins, the Red Wings probably have the edge heading into Game 7. They'll have to play in Anaheim, but they are coming off the high of winning in overtime and have actually won three OT games in this series. That is a telltale sign that the Red Wings aren't afraid of big moments, so they should be quite relaxed in the seventh and deciding game.

The pressure is firmly on the Ducks as they are the No. 2 seed and are in danger of letting the series slip away. Both teams have plenty of players with playoff experience, but Detroit seems to have more depth as opposed to Anaheim, who relies on about a line-and-a-half to do all of its scoring.

The Red Wings have plenty of guys who chip in offensively, including a third line featuring Damien Brunner and Joakim Andersson. Because of its depth, Detroit will win in seven.

Washington Capitals vs. New York Rangers

The series between the Washington Capitals and New York Rangers appeared to be one of the most evenly matched ones on paper heading into the playoffs. That has been proven true, as the Caps hold a 3-2 advantage after playing a number of close contests.

The Capitals and Rangers have played each other often over the past couple years, including in last year's postseason, when New York outlasted Washington in seven games in the second round.

Washington has the upper hand this year, though, and is one win away from knocking out the Blueshirts. This series has been an incredibly tight one, as four of the five games have been decided by one goal. Game 5 went to overtime and both teams had an opportunity to gain the advantage in the series, but Capitals forward Mike Ribeiro netted his first goal of the playoffs and his first career postseason OT goal, according to the Caps' Twitter feed.

This series has been played the way New York likes it, as the games have largely been low scoring with defense and goaltending ruling the day. Henrik Lundqvist has been outplayed by Braden Holtby between the pipes, though, and it can be argued that was the case last year as well.

While the series is too close not to go seven games, Washington has played better overall hockey throughout and will find a way to prevail in the seventh game.

Boston Bruins vs. Toronto Maple Leafs

The Boston Bruins and Toronto Maple Leafs carried their Northeast Division rivalry into the playoffs this season and have engaged in a highly entertaining series. The Bruins hold a 3-2 advantage after Toronto struck back in Game 5 to stay alive.

The Leafs shocked a lot of people this year by breaking their long playoff drought and competing with many of the Eastern Conference's elite teams, but the Bruins are clearly the better squad when push comes to shove.

Boston hasn't gotten the consistent play throughout its lineup that it has grown accustomed to, but center David Krejci has been playing out of his mind. He leads all players with five goals and 11 points in five games, including an overtime winner in Game 4. Despite his dominant play, Krejci refuses to take credit for Boston's 3-2 lead, according to the Bruins' official Twitter feed.

Soft-spoken Krejci gave a smile & shrug when asked about coming up big in the playoffs, "it happens," he said, & gave praise to his team^CS

Toronto is a gutsy team that won't go down willingly, but the Bruins have too much skill, grit and playoff experience to lose this series. Also, Boston has the advantage between the pipes, as TuukkaRask has been spectacular all season long. Look for a total team effort out of the Bruins in Game 6, as they will eliminate the Leafs and likely take on either the Capitals or Rangers in the second round.